Frequently Asked Questions

What is web RTI?

web RTI is a browser-based platform for viewing and processing Reflectance Transformation Imaging (RTI) and Polynomial Texture Map (PTM) files. Built for researchers, museums, and cultural heritage institutions, it enables anyone to upload raw RTI data and generate interactive web viewers — no plugins or specialized software required.

How does web RTI work?

Upload your .rti or .ptm files, and web RTI converts them into a web-compatible format directly in your browser. Once converted, the optimized web format is uploaded to our servers and becomes available as an interactive viewer where anyone can manipulate a virtual light source to explore surface details.

What file formats are supported?

web RTI supports the standard Reflectance Transformation Imaging (.rti) format and Polynomial Texture Map (.ptm) files.

Where does the file conversion happen?

All file conversion is performed locally in your browser using WebAssembly. Your original .rti and .ptm files are never uploaded to our servers. Only the resulting web-compatible format (tiled images and metadata) is stored, which is what powers the interactive viewer. This means conversion is private, fast, and doesn’t depend on server resources.

Can I use web RTI as a backup for my files?

No. web RTI stores only the converted web format, not your original .rti or .ptm files. Once you close the page or navigate away after conversion, the original files are discarded from your browser. You should always keep your own copies of the original data. web RTI is a viewing and sharing platform, not a backup service.

What technology powers web RTI?

web RTI is built on two open-source projects developed by the Visual Computing Lab at ISTI — CNR (Pisa, Italy):

• relight — handles file conversion from .rti/.ptm into web-compatible formats. Maintained by Federico Ponchio and contributors. github.com/cnr-isti-vclab/relight
• OpenLime — provides the interactive WebGL-based viewer for relightable images. github.com/cnr-isti-vclab/openlime

We are grateful to the Visual Computing Lab for their work on these excellent tools that make browser-based RTI viewing possible.

Do I need an account?

An account is required to create and manage collections. Viewing public collections does not require an account — anyone with the link can explore interactive RTI viewers.

Can I make my collections private?

Yes. When creating or editing a collection, you can choose between public and private visibility. Private collections are only accessible to you when signed in.

Is there a file size limit?

There are no fixed file size limits, but very large files may take longer to process in your browser. Since conversion happens locally, performance depends on your device’s processing power and available memory.

How can I share my collections?

Each public collection gets a permanent URL that you can share with anyone. Recipients can view and interact with the RTI files directly in their browser, with no software installation required.